Fuel injection pumps



April 7, 1954 w. FRIEDLANDER 3,127,841

FUEL INJECTION PUMPS Filed April 6, 1960 United States Patent 3,127,841FUEL INJECTIGN PUMPS William Friedlander, Esher, England, assignor toMono- Cam Limited, London, England, a company of Great Britain FiledApr. 6, 196%, Ser. No. 20,318 Claims priority, application Great BritainApr. 7, 1959 2 Claims. (1. 10341) This invention relates to improvementsin fuel injection pumps for internal combustion engines particularly,though not exclusively, compression-ignition engines. It is concernedwith improvements in such pumps of the kind (hereinafter referred to asthe kind specified) comprising a piston and cylinder pumping assembly inwhich the piston is driven by the engine so as to rotate and be axiallydisplaced in the cylinder to perform the injection stroke and thecylinder has one or more fuel inlet ports opening therein-to to admitfuel to the cylinder when the piston is at the bottom of its stroke andarranged normally to be blanked off by the piston during the injectionstroke of the piston.

There is a tendency for such engines to run in the reverse direction tothat intended when started up or when accelerated from low engine speedsand as this results in the vehicle, to which the engine is fitted, beingunexpectedly driven backwards, it can have disastrous results.

It is an object of the present invention to provide an improved fuelinjection pump of the kind specified which shall prevent the enginerunning in the reverse direction to that intended.

According to the present invention the piston of a fuel injection pumpof the kind specified is provided with means operative upon rotation ofthe piston in the direction opposite to that intended to maintain aninlet port in communication with the upper or operative end of thepiston during the effective part of an injection stroke and prevent fuelinjection taking place.

Preferably the means operative to.- maintain an inlet port incommunication with the upper'tor operative end of the piston comprises aslot formed in the cylindrical wall of the piston to extend away fromthe upper or operative end of the piston at an angle to the generatrixof said cylindrical wall in the direction opposite to that in which thepiston is intended to rotate.

One embodiment of the invention will now be described by way of example,reference being made to the accompanying drawings in which? FIG. 1 is anelevational view of a piston according to the present invention,

FIG. 2 is a fragmentary part elevational part sectional view showing thepiston of FIG. 1 at the bot-tom of its stroke in a cylinder, and

FIG. 3 is a view to a larger scale showing the position of an inlet-portrelative to the piston during an injection stroke, the inlet port beingshown in full lines for the correct forward-, rotation of the piston andbeing shown in dotted lines for reverse rotation of the piston.

The piston 1 illustrated in FIG. 1 is of known type having an upperoperative end 2 formed with an inoperative reduced diameter portion 3and being formed with an axial bore 4 extending from the upper orleading end of the portion 3 to a radial bore 5 which opens into a slot6 formed in the side wall of the piston 1 at a location to deliver fuelto an outlet port (not shown) on an injection stroke of the piston. Thepiston '1 is modified by the provision of a groove or slot 7 formed inthe cylindrical wall of the piston 1 and extending downwardly away fromthe operative end 2 at an angle to the generatrix of the cylindricalwall in a direction opice posite to that in which the piston 1 isintended to rotate when driven by the engine in the correct forwarddirection. The groove 7 may be substantially straight or helical and inthis example makes an angle of 50 with the generatrix of the curvedsurface of the piston, has a width of 1.54 mm, a depth of 1 mm. and aneffective length of 3 mm. The groove 7 may, as illustrated in FIG. 1,extend into the reduced diameter portion 3 of the piston 1 for ease ofmanufacture, although such an extension serves no useful purpose.

In FIG. 2 the operative end of the piston 1 is shown at the bottom ofits stroke prior to an injection stroke within a fragment of a fuelinjection pump which may be any suitable pump but which may, withadvantage, be a pump such as is described in my co-pending applicationSerial No. 8,763, dated February 15, 1960, and illustrated in FIGS. 1, 3or 4 thereof. The piston 1 is disposed for reciprocation in a cylinder 8formed in a pump body ,or housing 9, the cylinder 8 being closed by aplate 10 which may, as shown, have a port '11 communicating under thecontrol of governor means (not shown) with the low pressure side of thefuel injection pump to control the point in the injection stroke of thepiston 1 at which fuel is spilled to the low pressure side and hence tocontrol the injection period. The piston 1 is shown at the bottom of itsstroke in the position it assumes just prior to commencing an injectionstroke for correct forward running of the engine, the direction ofrotation being indicated by the arrow A. The fuel injection pumpembodying the arrangement described is intended to deliver fuel to fourengine cylinders, from equi-angularly disposed outlet ports (not shown)being provided in the pump body or housing 9, each communicating with anengine cylinder and each arranged to communicate with the slot 6 duringan injection stroke once per revolution of the piston .1. The piston 1is rotated by the engine in known manner and is connected to adiametrically extending arm carrying cam profiles (not shown) whichco-operate with four rollers (not shown) equi-angularly spaced about theaxis of rotation of the piston 1 so as to lift the piston 1 against theinfluence of spring means (not shown) four times during each completerevolution and so provide four injection strokes per revolution. It willbe appreciated that there is a dwell period between injection strokesduring which the piston 1 continues to be rotated. Four fuel inletpassages .12 open into the cylinder 8 through equi-angularly spacedinlet ports 13, and are so arranged that fuel is admitted to thecylinder 8 when the piston is at the bottom of its stroke.

In FIG. 3 the positions of an inlet port 13 relative to tr e groove '7at the commencement of an injection stroke, intermediate an injectionstroke and at the end of an injection stroke are denoted by 13a, 13b and130 respectively for the correct forward running of the engine. It willbe seen that shortly after commencing an injection stroke the inlet port13 is blanked-01f by the piston 1 and remains blanked-01f throughout theinjection stroke, the groove '7 being inoperative and injection takingplace in the normal manner through the axial bore 4, radial bore 5, slot6 and the appropriate outlet port.

if, however, the engine inadvertently reverses its direction of drive,the direction of rotation of the piston 1 will be reversed and duringthe dwell period referred to above will be rotated through an angle lessthan before commencing its injection stroke so that the position of aninlet port relative to the groove 7 at the instant of commencement of aninjection stroke will be that denoted in dotted lines and by thereference 13'a. At an intermediate point in the injection stroke therelative position of the inlet port is denoted by 1312, the port 13remaining in communication with the cylinder 8 through the groove 7. ItWill be seen therefore that during the injection stroke, with the enginerunning in the reverse direction an inlet port 13 remains incommunication with the upper or operative end 2 of the piston 1 by Wayof the groove 7 so that no injection can take place. It is possible thatat the end of the injection stroke of the piston 1 the inlet port 13will be blanked-off in the arrangement described but this is notmaterial as the upper end of the injection stroke of the piston 1 is notusually effective to provide injection as the pump is commonly arrangedto spill before the end of the injection stroke is reached. It will beappreciated that, if desired, the groove 7 may be suitably shaped anddimensioned so as to maintain the inlet port 13 in communication withthe upper or operative end 2 of the piston 1 throughout an injectionstroke of the piston when the engine is running in the reversedirection, although, as explained above, it is only necessary for thiscondition to exist during the effective part of the injection stroke. Asno injection takes place under the conditions described, it will be seenthat the engine cannot run in the direction opposite to that intended.

It will be appreciated that the arrangement described above may bemodified in a number of ways without departing from the scope or" theinvention. Thus, for example, instead of the cylinder 3 having a numberof inlet ports 13 corresponding to the number of injection strokes perrevolution of the piston 1, a single port 13 may be provided and thepiston 1 provided with a number of grooves 7 corresponding in number tothe number of injection strokes per revolution, or there may be provideda number of grooves 7 and a number of inlet ports 13. Thus it ispossible to achieve the desired result for a pump feeding four enginecylinders by providing two inlet ports 13 and two grooves 7, either theinlet ports 13 or the grooves 7 occurring at 180 intervals and thegrooves 7 or the inlet ports 13 being spaced 90 apart. Thus the productof the number of fuel inlet ports 13 and the number of grooves 7 shouldcorrespond to the number of engine cylinders to be served by the pump.

What I claim is:

1. In a fuel injection pump, in combination, a cylinder; an injectionpiston mounted in said cylinder for reciprocation through injection andretraction strokes thereof; said injection piston having an axial fuelinjection passage therethrough having a discharge opening through theinjection end thereof and having an. injection discharge port therefromthrough a side wall of said piston; said cylinder providing an inletport opening thereinto for supply of fuel to the injection end of saidcylinder for injection therefrom by and through said piston on injectionstrokes of the latter; said piston being also mounted for rotation insaid cylinder and being adapted to be rotated in one direction duringnormal operation thereof; said cylinder providing a discharge porttherefrom at the injection end thereof; said piston being provided withan angularly positioned slot therein disposed longitudinally thereof atan angle to the axis of said piston in a direction opposite thedirection of rotation of said piston in normal operation thereof; andsaid piston upon rotation thereof in the direction opposite saiddirection of normal rotation positioning said angularly disposed slot inopen communication With said inlet port during an injection stroke ofsaid piston for discharge of fuel from said cylinder through said inletport.

2. In a fuel injection pump, in combination, a cylinder; an injectionpiston reciprocally and rotatably mounted in said cylinder; said pistonhaving an axial fuel injection passage therethrough opening through theinjection end of said piston and having an injection discharge port fromsaid axial passage through the side wall of said piston; said cylinderhaving an inlet port opening through the side wall thereof for supply offuel into said cylinder for injection by said piston through said axialinjection passage on injection strokes of said piston; said piston oninjection strokes thereof blocking off said inlet port; said pistonbeing adapted for rotation in said cylinder in one direction duringnormal operation thereof; said cylinder having a discharge outlettherefrom at the injection end thereof for discharge of fueltherethrough from said cylinder; said piston having a slot formed in theside Wall thereof extending from the injection end of said pistoninwardly therealong at an angle to the generatrix of said piston wall inthe direction opposite the direction of rotation of said piston innormal operation thereof; and said piston when rotated in the directionopposite the direction of normal rotation thereof positioning said slotto open said inlet port to said cylinder on injection strokes of saidpiston for discharge of fuel from said cylinder through said inlet port.

References Cited in the file of this patent UNITED STATES PATENTS2,544,561 Meyer Mar. 16, 1951 2,778,351 Links Jan. 22, 1957 2,813,523Bischoff Nov. 19, 1957 2,839,040 High June 17, 1958 2,965,087 BischoifDec. 20, 1960 2,980,092 Dreisin Apr. 18, 1961 3,020,902 Sjoblom Feb. 13,1962

1. IN A FUEL INJECTION PUMP, IN COMBINATION, A CYLINDER; AN INJECTIONPISTON MOUNTED IN SAID CYLINDER FOR RECIPROCATION THROUGH INJECTION ANDRETRACTION STROKES THEREOF; SAID INJECTION PISTON HAVING AN AXIAL FUELINJECTION PASSAGE THERETHROUGH HAVING A DISCHARGE OPENING THROUGH THEINJECTION END THEREOF AND HAVING AN INJECTION DISCHARGE PORT THEREFROMTHROUGH A SIDE WALL OF SAID PISTON; SAID CYLINDER PROVIDING AN INLETPORT OPENING THEREINTO FOR SUPPLY OF FUEL TO THE INJECTION END OF SAIDCYLINDER FOR INJECTION THEREFROM BY AND THROUGH SAID PISTON ON INJECTIONSTROKES OF THE LATTER; SAID PISTON BEING ALSO MOUNTED FOR ROTATION INSAID CYLINDER AND BEING ADAPTED TO BE ROTATED IN ONE DIRECTION DURINGNORMAL OPERATION THEREOF; SAID CYLINDER PROVIDING A DISCHARGE PORTTHEREFROM AT THE INJECTION END THEREOF; SAID PISTON BEING PROVIDED WITHAN ANGULARLY POSITIONED SLOT THEREIN DISPOSED LONGITUDINALLY THEREOF ATAN ANGLE TO THE AXIS OF SAID PISTON IN A DIRECTION OPPOSITE THEDIRECTION OF ROTATION OF SAID PISTON IN NORMAL OPERATION THEREOF; ANDSAID PISTON UPON ROTATION THEREOF IN THE DIRECTION OPPOSITE SAIDDIRECTION OF NORMAL ROTATION POSITIONING SAID ANGULARLY DISPOSED SLOT INOPEN COMMUNICATION WITH SAID INLET PORT DURING AN INJECTION STROKE OFSAID PISTON FOR DISCHARGE OF FUEL FROM SAID CYLINDER THROUGH SAID INLETPORT.